By Bruce Rottink, Volunteer Nature Guide & Retired Research Forester
Tryon Creek State Natural Area (TCSNA) has 15 miles of hiking trails for anyone wanting to get out into a forested area and take a run or walk. You can enjoy nature at any season of the year. In certain places you can see spots where people have not done a good job of staying on the trails, and the results can be pretty stark. The photo below shows a spot along Old Main Trail where hoards of hikers have rambled off the trail to get an up-close view of the roots. The trampled area is now essentially bare of plant life. For clarification purposes, the hemlock in the picture got started long ago on top of a decaying log. The roots of the tree (yellow arrow) started growing inside the log. Many of them eventually made it down into the ground, so when the log rotted away, the roots were exposed above ground. In “exploring” this up close, lots of the people find this fascinating and climb up on top of the roots.
How much trampling can plants tolerate?
I was curious about how much trampling it takes to kill the plant life at TCSNA. After securing permission to set up a study on this question, I laid out a plan. I identified three small areas at TCSNA where waterleaf (Hydrophyllum tenuipes), a fairly common plant at the park, was virtually the only plant growing. These three areas were located some distance away from major trails to both minimize negative visual impacts on trail-walkers at the park, and to protect the plots from unplanned visitations from other people.
I then set up 6 “plots” at each of these locations. A “plot” was an area of ground of a size that could be covered by my boots when I stepped on it, as shown in the picture below. This was approximately 10” by 12”. To minimize the influence of each plot on other plots, each plot was at least 1 foot away from all other plots. This picture was not taken at an actual plot, but was taken in an area with fairly sparse waterleaf so that you could easily see my boots. An important thing to note is that there is a tiny area between my boots that did NOT get directly trampled.
The plots were set up on April 29, 2019. The individual plots were marked by white stakes with painted rings on them. The color of the rings on the stakes indicated when they were to be trampled. I visited the general areas for 15 consecutive days, and carried out the following trampling schedule:
Green Stakes = Never trampled
Blue Stakes = Trampled 1 time
Yellow Stakes = Trample 3 times (once every 5 days)
Red Stakes = Trample 5 times (once every 3 days)
Orange Stakes = Trample 15 times (once every day)
In the photos below, I have tried to make each photo large enough so that you could see the white stakes that mark the corners of the plots. This means that on the very edge of the photos are actually outside the plots that were trampled.
Results One Month After Trampling
The last trampling was conducted on May 13, 2019. One month later, on June 13, 2019, I revisited the plots to assess their status. All of the plots were selected because they were basically 100% covered with waterleaf. Photos of the plots from each of the three study areas are shown below. In each case, the point where the white stakes enter the soil mark the 4 corners of the plots. In almost all the photos, you cannot see the actual point where the stake entered the ground, but you can get a pretty fair idea of where it was.
Control Plots – Never Trampled
In general, after a month, all the control plots are fairly well covered with green waterleaf leaves. In Area 3 there was even one plant that flowered. I don’t know what created all the little holes in the leaves, but rest assured, there were many other areas in the park that exhibited this same pattern, so I’m doubtful it had anything to do with my study.
Plots Trampled 1 Time
Area 1 and 3 had some erect healthy looking leaves, even after being trampled 1 time. In Area 2, there were still some green leaves on the plot, but the stems were pretty much lying flat on the ground, not erect.
Plots Trampled 3 Times
Two of the three thrice-trampled plots still displayed a few green leaves, but compared to the controls, things were looking a little scant. In most cases, the green leaves on the plots were on stems that had been trampled down so that they now laid on the ground.
Plots Trampled 5 Times
In the 5 times trampled plot in Area 3, the red arrow marks the point where the stem emerges from the ground. This close to the corner of the plot, the stem may not have been stepped on directly at the point where it emerged from the soil. The plots in general, compared to the plots which were never stepped on, look pretty bleak.
Trample 15 Times
On the plots which were trampled 15 times, little or no waterleaf has survived.
Sometimes, the most interesting parts of a scientific study are the unexpected results. Here is a photo of an area that I walked through to get back to one of my study areas each day. This area started out as a solid bed of waterleaf. Can you figure out where I walked to get back to the study area?
So what’s the take-home lesson?
It’s pretty clear that the forest at TCSNA will get along much better if we all stay on the established trails. Is there cool stuff to see off the trail? You bet there is. But seeing it comes at a price for Nature, and we should all keep in mind this sign posted in an area that had lots of off-trail trampling:
The renovation of the Nature Center is complete and new exhibits have been installed in the lobby. Construction work was paid for by the Engineering Division of the Oregon Parks and Recreation Department and completed by Colton Homes and subcontractors. New exhibits were paid for by the agency and designed by Alchemy of Design.
The building is open 9am-4pm, every day of the week. Come and check it out!
See post here about the original scope of the project.
Up next? A few things are being completed including adding a new brochure holder, reinstalling the events bulletin board, acquiring a new Open/Closed sign, and updating and repairing additional exhibits for the Kraft Room.
The renovation of the Nature Center is nearly complete. New flooring has been installed, the new front entry way is nearly complete, the front desk counters are in, and new exhibits have been installed in the lobby.
The crew from Colton Construction is finishing up and the Nature Center is scheduled to reopen on Monday, July 22nd.
See post here about the scope of the project.
Up next? Final touches, re-installation of exhibits in the Kraft Room, and setting up the front desk and store.